QmlDesigner: Provide a descriptive message for invalid IDs

Fixes: QDS-5044
Change-Id: I12f78851f5200e417fe6f323a0773587400cd90f
Reviewed-by: Johanna Vanhatapio <johanna.vanhatapio@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/components/propertyeditor/propertyeditorview.cpp

@@ -163,8 +163,9 @@ void PropertyEditorView::changeValue(const QString &name)
             m_locked = true;
             value->setValue(m_selectedNode.id());
             m_locked = false;
-            if (!QmlDesigner::ModelNode::isValidId(newId))
+            QString errMsg = QmlDesigner::ModelNode::getIdValidityErrorMessage(newId);
-                Core::AsynchronousMessageBox::warning(tr("Invalid ID"),  tr("%1 is an invalid ID.").arg(newId));
+            if (!errMsg.isEmpty())
+                Core::AsynchronousMessageBox::warning(tr("Invalid ID"),  errMsg.arg(newId));
             else
                 Core::AsynchronousMessageBox::warning(tr("Invalid ID"),  tr("%1 already exists.").arg(newId));
         }

src/plugins/qmldesigner/designercore/include/modelnode.h

@@ -168,6 +168,8 @@ public:
     void setIdWithRefactoring(const QString &id);
     void setIdWithoutRefactoring(const QString &id);
     static bool isValidId(const QString &id);
+    static QString getIdValidityErrorMessage(const QString &id);
+
     bool hasId() const;
 
     Model *model() const;

src/plugins/qmldesigner/designercore/model/modelnode.cpp

@@ -212,6 +212,29 @@ bool ModelNode::isValidId(const QString &id)
     return id.isEmpty() || (!idContainsWrongLetter(id) && !idIsQmlKeyWord(id) && !isIdToAvoid(id));
 }
 
+QString ModelNode::getIdValidityErrorMessage(const QString &id)
+{
+    if (isValidId(id))
+        return {}; // valid
+
+    if (id.at(0).isUpper())
+        return QObject::tr("ID cannot start with an uppercase character.");
+
+    if (id.at(0).isDigit())
+        return QObject::tr("ID cannot start with a number.");
+
+    if (id.contains(' '))
+        return QObject::tr("ID cannot include whitespace.");
+
+    if (idIsQmlKeyWord(id))
+        return QObject::tr("%1 is a reserved QML keyword.");
+
+    if (isIdToAvoid(id))
+        return QObject::tr("%1 is a reserved property keyword.");
+
+    return QObject::tr("ID includes invalid characters.");
+}
+
 bool ModelNode::hasId() const
 {
     if (!isValid())